In an optical device such as a light emitting device or a light receiving device, and a package for such optical device, there have been the following technological requirements:
(a) It must have a light introducing structure which is transparent to light;
(b) It must be wired as by die bonding or wire bonding to lead electrode terminals in and out of it;
(c) Its chip must be sealed hermetically; and
(d) It must have a high coupling efficiency with an optical fiber. That is, a light emitting diode chip or a photodiode chip must be sufficiently close to the optical fiber in end faces and must have a large opening angle. Further, the chip must have a clean light receiving surface which is not stained with paste or like material.
The present invention intends to meet all these criteria, particularly the requirement (d) above.